void main() 
{
    char str[100] = "0";
    
    int i=0,n;
    for(i=1,n=1;i<99;i++,n++)
    {
        printf("%s\n",str); 
        printf("len = %d\n",strlen(str));
        if(i<10)
        {
            str[i] = i+'0';
        }
        else
        {   
            str[n] = i/10 + '0';
            n++;
            str[n] = i%10 + '0';   
        }     
    }
}